The prior art is replete with motors, for example, of the synchronous type which include a rotor having a disc-shaped body including a plurality of permanently magnetized poles of alternately opposite polarity, a stator having a core with at least one pair of spaced-apart stator pole pieces defining an air gap and means for supporting the rotor for rotation within the gap. The supporting means comprises a shaft which, also, may support a drive pinion or other form of input to a mechanical movement, for example, of a timepiece and which, in turn, is supported for rotation in a bearing disposed at or within the region of opposed ends of the shaft. Typical prior art constructions are those illustrated in U.S. Pat. Nos. 3,803,433 to Ingenito and 3,869,627 to Ingenito et al., as well as other pending applications, all of which are assigned to the assignee of the present invention. While these motors have received commercial acceptance and are in widespread use in driving the mechanical movement of a timepiece they have been found by some to suffer from a drawback, namely, they are considered to generate noise at a level which is unacceptable. The noise results from the rattle of a rotating member in a bearing possibly caused by too large a clearance between the end of the shaft and the bearing walls, improper lubrication of the bearing or loss of lubrication through extended use, to name a few reasons. In terms of the total amount of ambient noise the rattling noise, while not great, has been determined the direct cause of many returns of motors used to drive timepieces both in home and automobile applications.
The present invention then is directed to and has as its main object that of improving upon motors such as of the afore-mentioned types as well as others thereby to eliminate or at least substantially reduce this type of generated noise whereby the motors will have better acceptance. While the concept of the present invention is discussed in terms of the combination with a motor, as will become apparent, it has more universal application. Thus, the concept may be used both with wheels and gears, typically formed of "ferrous" material, whereby a stationary magnet is positioned at their edge.